It is frequently desirable or imperative to reliably know the precise location of an object, and to be able to determine that location on a reoccurring basis. The object may be highly mobile or relegated to use in a confined area or confined areas.
Objects being transported by vehicle are highly mobile. With respect to such objects which are dangerous or controlled, as for example toxic waste and nuclear materials, it is desirable to be able to reliably monitor their location during transport between locations. Such monitoring may be continuous or may be from point-to-point.
Digital signatures represent objects which may be intended to be used only in Highly localized areas. Digital signatures involve the use of cryptographic keys to sign messages. For legal or security reasons it is at times important to prove or establish that these digital signatures are being generated within a particular jurisdiction, a specific complex, building or room. For example, a digital signature of a bank employee that is used in various bank transactions would advantageously be confined to the location of a guarded bank facility. An employee's computer sign-on token may be limited to use at a specified location such as home or the office. For audit and billing purposes the location of requestors for access to sensitive material or databases is needed.
There are other environments in which it is important to reliably know the location of an object. A supplier of electronic broadcasts may need to screen certain locales to black-out reception of certain sports broadcasts, concerts, etc., or other signals such as electronic gambling events. In other instances, satellite decoder boxes limited to use in licensed areas are needed.
The present invention uses unique location certificates to track goods and wares during shipment, establish the location of participants in a network, determine the location at which a digital signature was performed, ascertain the validity of objects which are expected or mandated to be present within certain geographic bounds and control the use of security or sensitive devices by limiting their operation to certain locations.
Determining the location of an object or event involves the employment of a position determination unit. In accordance with an exemplary embodiment of the present invention, the position determination unit operates on the reception of Loran or Global Positioning System (GPS) signals to establish its location. The unit may continuously determine its position or compute its position on request. A secure authorization unit functions to authenticate the location information reported to a requestor. Specifically, the secure authorization unit, through the use of its private digital signature key and a certificate authenticates that the requested position information is provided by a trusted location certification unit.
Three basic systems are set forth as exemplary embodiments of the present invention, one with a basic location certification unit (LCU), a second using a sensor, and a third operating on a two-way communication link between beacons and a sensor in the LCU. In addition, many variations and modifications of these systems are disclosed, and others would be readily apparent to those skilled in this art. In these systems, there is the ever present danger of attempts by unauthorized individuals to breach the security of the system, as for example, by the use of sophisticated spoofing techniques where false radio broadcasts on Loran or GPS frequencies may be employed to cause the position determination unit to compute a position other than its actual position. The systems of the present invention use techniques and procedures to safeguard against such eventualities.